First, we can see that he used the Distributive property. Then after that, he used the Additive property. After that, he combined like terms and the used the additive property again. Finally, he used the divisive property.
Answer:

Step-by-step explanation:
Given


Required

First, calculate 
We have:

This gives:

Substitute 


Substitute 



Split

This gives

12 inches Bc angle J is 42 degrees
Answer:
add all the sides together
a+b+c+d